The disclosure relates generally to rotor assemblies, and more particularly to blade or bucket design and mounting in turbine rotors.
A rotor includes a plurality of blades or buckets whose roots are typically mounted on a rotating body, such as a shaft or the like, often referred to as a wheel. Each blade or bucket root may include a profile that is typically shaped to be retained against radial motion when mounted in a groove in the body so that the blade may slide in the groove but not come out of the groove. For example, the blade root and groove may include complementary dovetails including a bucket or blade hook and a wheel hook that cooperate to retain the bucket dovetails in the groove. To enable insertion of the bucket roots into the groove, the blade hook region is typically cut to form an assembly gate. The assembly gate is generally one bucket width along the circumference. Special arrangements must be made to retain the blade(s) at the assembly gate. The assembly gate is typically cut through wheel hooks in the groove, which may reduce the load bearing capacity of the gate area. Additionally, natural frequencies of the rotor may be affected by the assembly gate, as may balancing of the rotor.